Preparation, characterization, and use of an antiserum specific for 2‘,5‘-oligoadenylates

Determination of the level of the core of 2',5'-oligoadenylates by high performance liquid chromatography

A simple and rapid method for analysis of the core of 2',5'-oligoadenylates, mainly based on the use of high performance liquid chromatography (HPLC), is described. Perchloric acid extracts of tissues or cells were first treated with nuclease P1. Portions of the extracts were then digested with alkaline phosphatase. HPLC analysis of the extracts was performed on a column system composed of an Ultrasphere ODS precolumn (4.6 x 45 mm) and an Ultrasphere Octyl column (4.6 x 250 mm) by stepwise elution using a 50 mM ammonium phosphate buffer, pH 7, containing 3.5 and 7% methanol. Three species of the core of 2',5'-oligoadenylates (dimer, trimer and tetramer) from a number of samples were eluted separately with 7% methanol, and the concentration of each core was directly estimated using constant values calculated with the standard core. The level of the core of 2',5'-oligoadenylates in tissues and cells determined by our method is similar to that reported by other authors who used biological, radiobinding or radioimmunological assays.

Enzyme immunoassay of 2'-5'-oligoadenylates at the femtomole level

We have developed a competition enzyme immunoassay (EIA) for 2'-5'-oligoadenylates [p kappa(A2'p5')nA; 0 less than or equal to kappa less than or equal to 3; 1 less than or equal to n] based on an anti-A2'p5' A monoclonal antibody coated onto 96-well polystyrene plates and A2'p5' A peroxidase as a marker. It permits measurement of 5'OH(A2'p5')nA as such and p kappa(A2'p5')nA after alkaline phosphatase hydrolysis, with a detection threshold of 5 X 10(-12) M. All 2'-5'-oligomers were assayed with similar sensitivity. ATP and adenosine did not interfere at concentrations up to 10(6)-fold higher than those of 2'-5'-oligoadenylates. Reproducibility, stability of reagents and correlation with the radioimmunoassay were good. As such, this EIA is a suitable tool for studying the 2-5A system, particularly, in clinical investigations: the initial velocity of 2-5A synthetase can be determined on 10,000 cells without purification and the level of 2'-5'-oligoadenylates can be assayed on less than 1 ml of blood.

The effect of pristane on ascites tumor formation and monoclonal antibody production

Preinjection of mice 10 days before intraperitoneal injections of hybridomas gives optimum development of ascites tumors with respect to the rate at which tumors form, percentage of mice developing tumors, volume of ascites fluid produced, and concentration of monoclonal antibody in ascites fluid. The dose of pristane injected has little or no effect on ascites formation down to 0.1 ml of pristane.

Functional analysis of 2-5A-dependent RNase and 2-5a using 2',5'-oligoadenylate-cellulose

2-5A is an intracellular effector that has been implicated in interferon action, hormonal regulation, and cell growth control. 2-5A action is mediated through its activation of 2-5A-dependent RNase (RNase L, RNase F). Affinity resins [2-5A-cellulose and core (2-5A)-cellulose] were chemically synthesized for purification and immobilization of 2-5A-dependent RNase from mouse L cells and rabbit reticulocyte lysates. The breakdown of poly(U)-[3'-32P]Cp to acid-soluble fragments was demonstrated using the 2-5A-dependent RNase:2-5A -cellulose complex; this activity was enhanced by adding (free) 2-5A. In contrast, RNase activity was measured from the 2-5A-dependent RNase:core (2-5A)-cellulose complex only after the addition of free 2-5A. The rabbit reticulocyte 2-5A-dependent RNase is activated only by tetramer or higher oligomers of 2-5A; therefore there was breakdown of poly(U)-[3'-32P]Cp using core (2-5A)-cellulose-bound reticulocyte 2-5A-dependent RNase after addition of tetramer 2-5A but there was no poly(U) degradation in the presence of trimer 2-5A. The absence of significant general nuclease in the assays was demonstrated by the resistance to breakdown of poly(C)-[3'-32P]Cp (not susceptible to 2-5A-dependent RNase). Moreover, core (2-5A)-cellulose was used to develop a sensitive (subnanomolar) assay for the detection of authentic 2-5A. 2-5A, or the material to be tested, was added to mouse L-cell 2-5A-dependent RNase:core (2-5A)-cellulose complex in the presence of poly(U)-[3'-32P]Cp. The concentration of 2-5A in the sample could be measured from the amount of poly(U) degradation. Several closely related analogs of 2-5A were tested and found to be completely inactive. The technology described herein may be applied to the study of the regulation of 2-5A-dependent RNase, the detection of 2-5A from cells and tissues, and other aspects of the 2-5A system.

Activation of the ppp(A2'p)nA system in interferon-treated, herpes simplex virus-infected cells and evidence for novel inhibitors of the ppp(A2'p)nA-dependent RNase

High doses (100-1000 reference units/ml) of alpha or beta interferons are required to inhibit the growth of herpes simplex virus types I and II (HSV-I and HSV-II) in human Chang cells. In contrast, much lower doses (10-100 reference units/ml) of interferon inhibit replication of encephalomyocarditis virus (EMCV) in these cells. In the HSV-infected cells these high doses did not prevent the virus-induced shut off of host protein synthesis. The interferons were more effective in reducing the virus yield of HSV-I than of HSV-II. At the above concentrations they inhibited HSV-I protein synthesis but had little apparent effect on that of HSV-II. Similar amounts of (2'-5')oligo(adenylate)s were synthesised in response to HSV-I, HSV-II and EMCV infection of Chang cells after treatment with alpha or beta interferons. No (i.e. less than 1 nM) (2'-5')oligo(adenylate)s were found in control cells or on virus infection alone. Only low levels of ppp(A2'p)nA-specific rRNA cleavage were observed in the interferon-treated HSV-infected cells. In contrast, high levels were found in response to EMCV, despite the fact that ppp(A2'p)nA accumulated to similar levels with each of the three viruses in these cells. High-performance liquid chromatographic analysis of material from interferon-treated Chang cells 18 h after infection with HSV-I or HSV-II, combined with radiobinding, radioimmune and rRNA cleavage assays, confirmed the presence of ppp(A2'p)2A and ppp(A2'p)3A at greater than nanomolar concentration. In addition, apparently equivalent amounts of two other putative (2'-5')oligo(adenylate) derivatives which compete in the radiobinding and radioimmune assays, were present. These compounds were only weak activators of the ppp(A2'p)nA-dependent RNase and under appropriate conditions were capable of inhibiting the activation of this RNase by authentic ppp(A2'p)nA. The presence of these potentially inhibitory compounds provides a possible explanation for the relatively low levels of activation of the ppp(A2'p)nA-dependent RNase in interferon-treated, HSV-infected Chang cells.